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Fix DNS record JSON parsing for MCNS response format

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MCNS returns records wrapped in {"records": [...]} envelope with
uppercase field names (ID, Name, Type, Value), not bare arrays
with lowercase fields.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Kyle Isom
2026-03-27 15:12:43 -07:00
parent 76247978c2
commit 2bda7fc138
2 changed files with 18 additions and 16 deletions
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18
internal/agent/dns.go
View File

@@ -28,11 +28,11 @@ type DNSRegistrar struct {
// dnsRecord is the JSON representation of an MCNS record. // dnsRecord is the JSON representation of an MCNS record.
type dnsRecord struct { type dnsRecord struct {
ID int `json:"id"` ID int `json:"ID"`
Name string `json:"name"` Name string `json:"Name"`
Type string `json:"type"` Type string `json:"Type"`
Value string `json:"value"` Value string `json:"Value"`
TTL int `json:"ttl"` TTL int `json:"TTL"`
} }
// NewDNSRegistrar creates a DNSRegistrar. Returns (nil, nil) if // NewDNSRegistrar creates a DNSRegistrar. Returns (nil, nil) if
@@ -157,11 +157,13 @@ func (d *DNSRegistrar) listRecords(ctx context.Context, serviceName string) ([]d
return nil, fmt.Errorf("list records: mcns returned %d: %s", resp.StatusCode, string(body)) return nil, fmt.Errorf("list records: mcns returned %d: %s", resp.StatusCode, string(body))
} }
var records []dnsRecord var envelope struct {
if err := json.Unmarshal(body, &records); err != nil { Records []dnsRecord `json:"records"`
}
if err := json.Unmarshal(body, &envelope); err != nil {
return nil, fmt.Errorf("parse list response: %w", err) return nil, fmt.Errorf("parse list response: %w", err)
} }
return records, nil return envelope.Records, nil
} }
// createRecord creates an A record in the zone. // createRecord creates an A record in the zone.

16
internal/agent/dns_test.go
View File

@@ -39,7 +39,7 @@ func TestEnsureRecordCreatesWhenMissing(t *testing.T) {
if r.Method == http.MethodGet { if r.Method == http.MethodGet {
// List returns empty — no existing records. // List returns empty — no existing records.
w.Header().Set("Content-Type", "application/json") w.Header().Set("Content-Type", "application/json")
_, _ = w.Write([]byte("[]")) _, _ = w.Write([]byte(`{"records":[]}`))
return return
} }
gotMethod = r.Method gotMethod = r.Method
@@ -90,9 +90,9 @@ func TestEnsureRecordSkipsWhenExists(t *testing.T) {
srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method == http.MethodGet { if r.Method == http.MethodGet {
// Return an existing record with the correct value. // Return an existing record with the correct value.
records := []dnsRecord{{ID: 1, Name: "myservice", Type: "A", Value: "192.168.88.181", TTL: 300}} resp := map[string][]dnsRecord{"records": {{ID: 1, Name: "myservice", Type: "A", Value: "192.168.88.181", TTL: 300}}}
w.Header().Set("Content-Type", "application/json") w.Header().Set("Content-Type", "application/json")
_ = json.NewEncoder(w).Encode(records) _ = json.NewEncoder(w).Encode(resp)
return return
} }
createCalled = true createCalled = true
@@ -124,9 +124,9 @@ func TestEnsureRecordUpdatesWrongValue(t *testing.T) {
srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method == http.MethodGet { if r.Method == http.MethodGet {
// Return a record with a stale value. // Return a record with a stale value.
records := []dnsRecord{{ID: 42, Name: "myservice", Type: "A", Value: "10.0.0.1", TTL: 300}} resp := map[string][]dnsRecord{"records": {{ID: 42, Name: "myservice", Type: "A", Value: "10.0.0.1", TTL: 300}}}
w.Header().Set("Content-Type", "application/json") w.Header().Set("Content-Type", "application/json")
_ = json.NewEncoder(w).Encode(records) _ = json.NewEncoder(w).Encode(resp)
return return
} }
gotMethod = r.Method gotMethod = r.Method
@@ -160,9 +160,9 @@ func TestRemoveRecordDeletes(t *testing.T) {
srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if r.Method == http.MethodGet { if r.Method == http.MethodGet {
records := []dnsRecord{{ID: 7, Name: "myservice", Type: "A", Value: "192.168.88.181", TTL: 300}} resp := map[string][]dnsRecord{"records": {{ID: 7, Name: "myservice", Type: "A", Value: "192.168.88.181", TTL: 300}}}
w.Header().Set("Content-Type", "application/json") w.Header().Set("Content-Type", "application/json")
_ = json.NewEncoder(w).Encode(records) _ = json.NewEncoder(w).Encode(resp)
return return
} }
gotMethod = r.Method gotMethod = r.Method
@@ -195,7 +195,7 @@ func TestRemoveRecordNoopWhenMissing(t *testing.T) {
srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
// List returns empty. // List returns empty.
w.Header().Set("Content-Type", "application/json") w.Header().Set("Content-Type", "application/json")
_, _ = w.Write([]byte("[]")) _, _ = w.Write([]byte(`{"records":[]}`))
})) }))
defer srv.Close() defer srv.Close()